Process for the preparation of bis(acyl)phospinic acid sylyl esters

ABSTRACT

The present invention refers to a process for the preparation of a bis(acyl)phosphinic acid silyl ester of the general formula (I), wherein R 1 , R 2 , R 3 , R 4 , R 5 , R 7 , R 8 , R 9 , R 10  and R 11  are the same or different and are independently selected from H, halogen, linear or branched C 1 -C 20 -alkyl, linear or branched C 2 -C 8 -alkenyl, C 1 -C 8 -alkoxy, C 2 -C 8 -alkenyloxy, C 3 -C 8 -cycloalkyl, C 6 -C 12 -aryl, C 3 -C 8 -cycloalkoxy, C 7 -C 12 -arylalkoxy, C 9 -C 15 -alkenylarylalkoxy, nitro-, C 6 -C 12 -arylsulfonyl, 4-alkylarylsulfonyl, C 1 -C 20 -alkylcarboxy, C 1 -C 8 -alkoxycarbonyl, SR 12 , NHR 12  or NR 12 R 13  with R 12  and R 13  being independently selected from H, linear or branched C 1 -C 20 -alkyl, linear or branched C 2 -C 8 -alkenyl and C 3 -C 8 -cycloalkyl, and an O-, S- or N-containing 5- or 6-membered heterocyclic ring; R 6  is OSiR 14 R 15 R 16  with R 14 , R 15  and R 16  being independently selected from linear or branched C 1 -C 20 -alkyl or C 6 -C 12 -aryl; as well as the bis(acyl)phosphinic acid silyl ester and the bis(acyl)phosphinic acid obtained by the process.

FIELD OF THE INVENTION

The present invention refers to a process for the preparation of abis(acyl)phosphinic acid silyl ester of the general formula I,

wherein R₁, R₂, R₃, R₄, R₅, R₇, R₈, R₉, R₁₀ and R₁₁ are the same ordifferent and are independently selected from H, halogen, linear orbranched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy,C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl, C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy,C₇-C₁₂-arylalkoxy, C₉-C₁₅-alkenylarylalkoxy, nitro-,C₆-C₁₂-arylsulfonyl, 4-alkylarylsulfonyl, C₁-C₂₀-alkylcarboxy,C₁-C₈-alkoxycarbonyl, SR₁₂, NHR₁₂ or NR₁₂R₁₃ with R₁₂ and R₁₃ beingindependently selected from H, linear or branched C₁-C₂₀-alkyl, linearor branched C₂-C₈-alkenyl and C₃-C₈-cycloalkyl, and an O-, S- orN-containing 5- or 6-membered heterocyclic ring; R₆ is OSiR₁₄R₁₅R₁₆ withR₁₄, R₁₅ and R₁₆ being independently selected from linear or branchedC₁-C₂₀-alkyl or C₆-C₁₂-aryl; as well as the bis(acyl)phosphinic acidsilyl ester and the bis(acyl)phosphinic acid obtained by the process.

BACKGROUND OF THE INVENTION

Bis(acyl)phosphine oxides (BAPOs) are well established and are extremelyefficient photoinitiators for the industrial curing of pigmented orclear coatings, adhesives, inks, photoresists, printing plates, anddental applications. The most prominent commercial product of this classis Omnirad 819, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide,formerly known as Irgacure 819.

Since long, there is a high demand for liquid and/or water solubleBAPOs. Many efforts have been undertaken to get to such compounds, mostof the processes consist expensive or laborious procedures. For example,WO 2012/012067 A1 discloses the synthesis of alkylbis(mesitoyl)phosphinates starting from dialkyl hydrogen phosphites.Only n-butyl bis(2,4,6-trimethylbenzoyl)phosphinate was given as anexample but without any information on yield or product properties. Itis to be noted that the example could not be reproduced in theapplicant's lab and does not seem to be reliable.

A water-compatible form of Irgacure 819 is available as a waterdispersion but a stable BAPO solution in water is not yet available onthe market. Such formulations are highly desirable for potential ink-jetand LED applications. In WO 2014095724 A1, and G. Müller, M. Zalibera,G. Gescheidt, A. Rosenthal, G. Santiso-Quinones, K. Dietliker, and H.Grützmacher, Macromol. Rapid Commun. 2015, 36, 553, a syntheticprocedure for a water-soluble BAPO derivative, the so-called BAPO—OH(bis(mesitoyl)phosphinic acid), is described. Many interestingphotoactive derivatives, including lithium, sodium, potassium andammonium salts as well as other water-soluble organic derivatives can besynthesized starting from the parent compound. However, the only knownsynthetic procedure for BAPO—OH suffers from severe limitations,rendering its synthesis costly, inconvenient or time-consuming. Moreprecisely, the synthesis method for BAPO—OH makes use of metalation ofwhite or red phosphorus or halogen-metal exchange of phosphorustrichloride. Even though the reaction proceeds with good to moderateyield, handling of white phosphorus is extremely dangerous due to itsphysical and toxicological properties. When starting from red phosphorusor phosphorus trichloride, the yields are significantly lower. Acomplexing solvent is imperative, causing extra costs compared tostandard solvents. In addition, an alkali metal is required, thusnecessitating the corresponding special equipment for industrial scaleproduction.

Therefore, there is a continuous need in the art for providing a processfor the preparation of bis(acyl)phosphinic acids. Furthermore, it isdesirable to provide a process for the preparation of an intermediatecompound which avoids elaborate processing steps for obtaining thedesired bis(acyl)phosphinic acids. Furthermore, it is desirable that theintermediate product can be easily prepared. In addition thereto, it isdesirable to provide a process for the preparation ofbis(acyl)phosphinic acids which avoids the use of metallic sodium orlithium in combination with undesirable phosphorus compounds such as anallotrope of phosphorus, e.g. white or red phosphorus, phosphorustrichloride, alkyl or aryl phosphine, or dialkyl or diaryl phosphinebecause of their volatility, bad smell, toxicity and susceptibility toair and fire. Furthermore, it is desirable to provide a process whichallows for the preparation of bis(acyl)phosphinic acids which are noteasily prepared by the processes of the prior art.

Accordingly, it is an object of the present invention to provide aprocess for the preparation of a compound which can be further convertedinto bis(acyl)phosphinic acids. It is an even further object of thepresent invention to provide a process for the preparation of thisintermediate product and the bis(acyl)phosphinic acid without elaborateprocessing steps for obtaining the compounds. It is an even furtherobject of the present invention to provide a process for the preparationof bis(acyl)phosphinic acids which avoids the use of metallic sodium orlithium in combination with undesirable phosphorus compounds such aswhite phosphorus, red phosphorus, phosphorus trichloride, alkyl or arylphosphine, or dialkyl or diaryl phosphine. It is another object of thepresent invention to provide a process which allows for the preparationof bis(acyl)-phosphinic acids which are not easily prepared by theprocesses of the prior art.

SUMMARY OF THE INVENTION

The foregoing and other objects are solved by the subject-matter of thepresent invention.

According to a first aspect of the present invention, a process for thepreparation of a bis(acyl)phosphinic acid silyl ester of the generalformula I is provided,

wherein R₁, R₂, R₃, R₄, R₅, R₇, R₈, R₉, R₁₀ and R₁₁ are the same ordifferent and are independently selected from H, halogen, linear orbranched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy,C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl, C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy,C₇-C₁₂-arylalkoxy, C₉-C₁₅-alkenylarylalkoxy, nitro-,C₆-C₁₂-arylsulfonyl, 4-alkylarylsulfonyl, C₁-C₂₀-alkylcarboxy,C₁-C₈-alkoxycarbonyl, SR₁₂, NHR₁₂ or NR₁₂R₁₃ with R₁₂ and R₁₃ beingindependently selected from H, linear or branched C₁-C₂₀-alkyl, linearor branched C₂-C₈-alkenyl and C₃-C₈-cycloalkyl, and an O-, S- orN-containing 5- or 6-membered heterocyclic ring; R₆ is OSiR₁₄R₁₅R₁₆ withR₁₄, R₁₅ and R₁₆ being independently selected from linear or branchedC₁-C₂₀-alkyl or C₆-C₁₂-aryl, the process comprising the steps of

-   -   a) heating ammonium hypophosphite with a silylating agent for        obtaining a bis(silyl ether)phosphine, and    -   b) reacting the bis(silyl ether)phosphine obtained in step a)        with a compound of the general formula IIa and/or IIb,

-   -   wherein R₁, R₂, R₃, R₄ and R₅ and/or R₇, R₈, R₉, R₁₀ and R₁₁ are        as defined above; Z is halogen.

The inventors surprisingly found out that such a process is suitable forthe preparation of a bis(acyl)phosphinic acid silyl ester which can beeasily converted into bis(acyl)phosphinic acids and avoids elaborateprocessing steps for obtaining the bis(acyl)phosphinic acid silyl esterand the desired bis(acyl)phosphinic acids. Furthermore, the processallows the preparation of the bis(acyl)phosphinic acids without the useof metallic sodium or lithium in combination with undesirable phosphoruscompounds such as white phosphorus, red phosphorus, phosphorustrichloride, alkyl or aryl phosphine, or dialkyl or diaryl phosphine. Inaddition thereto, the process allows the preparation ofbis(acyl)phosphinic acids which are not easily accessible by theprocesses of the prior art.

Advantageous embodiments of the inventive process are defined in thecorresponding sub-claims.

According to one embodiment, R₁, R₃ and R₅ and/or R₇, R₉ and R₁₁ are thesame.

According to another embodiment, R₁, R₃ and R₅ and/or R₇, R₉ and R₁₁ arethe same and are selected from linear or branched C₁-C₂₀-alkyl,preferably linear or branched C₁-C₁₈-alkyl, more preferably linear orbranched C₁-C₁₂-alkyl and most preferably linear C₁-C₈-alkyl.

According to yet another embodiment, R₂ and R₄ and/or R₈ and R₁₀ are thesame, preferably R₂ and R₄ and/or R₈ and R₁₀ are different from R₁, R₃and R₅ and/or R₇, R₉ and R₁₁.

According to one embodiment, R₂ and R₄ and/or R₈ and R₁₀ are the sameand are H.

According to another embodiment, Z is selected from chloro, bromo andiodo, preferably chloro.

According to yet another embodiment, step a) is carried out under aninert gas atmosphere and/or without the addition of a solvent.

According to one embodiment, the bis(silyl ether)phosphine obtained instep a) is mixed with an organic solvent, preferably an aprotic organicsolvent, before process step b) is carried out.

According to another embodiment, the bis(silyl ether)phosphine obtainedin step a) is subjected to process step b) without purification andisolation of the silylated product obtained in step a)

According to yet another embodiment, step a) is carried out at atemperature in the range from 100 to 130° C., preferably in the rangefrom 105 to 125° C. and most preferably in the range from 110 to 120° C.and/or step b) is carried out at a temperature in the range from −78 to+50° C., preferably in the range from 0 to 40° C., more preferably inthe range from 0 to 30° C., and most preferably in the range from 0 to25° C.

According to one embodiment, step b) is carried out in that theequivalent weight ratio of the compound of the general formula IIaand/or IIb to the ammonium hypophosphite of step a) [IIa and/orIIb:P-compound] is in the range from 3.5:1 to 1.5:1 and preferably inthe range from 2.5:1 to 1.8:1.

According to another embodiment, process step a) and/or step b) isrepeated one or more times.

According to yet another embodiment, the process comprises a furtherstep c) of hydrolyzing the bis(acyl)phosphinic acid silyl ester obtainedin step b) such as to obtain a bis(acyl)phosphinic acid of the generalformula III

wherein R₁, R₂, R₃, R₄, R₅, R₇, R₈, R₉, R₁₀ and R₁₁ are the same ordifferent and are independently selected from H, halogen, linear orbranched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy,C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl, C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy,C₇-C₁₂-arylalkoxy, C₉-C₁₅-alkenylarylalkoxy, nitro-,C₆-C₁₂-arylsulfonyl, 4-alkylarylsulfonyl, C₁-C₂₀-alkylcarboxy,C₁-C₈-alkoxycarbonyl, SR₁₂, NHR₁₂ or NR₁₂R₁₃ with R₁₂ and R₁₃ beingindependently selected from H, linear or branched C₁-C₂₀-alkyl, linearor branched C₂-C₈-alkenyl and C₃-C₈-cycloalkyl, and an O-, S- orN-containing 5- or 6-membered heterocyclic ring; R₆ is OH.

According to one embodiment, step c) is carried out at a temperature inthe range from −78 to +50° C., preferably in the range from 0 to 40° C.,more preferably in the range from 0 to 30° C., and most preferably inthe range from 2 to 28° C.

According to a further aspect of the present invention, abis(acyl)phosphinic acid silyl ester of the general formula I,

wherein R₁, R₂, R₃, R₄, R₅, R₇, R₈, R₉, R₁₀ and R₁₁ are the same ordifferent and are independently selected from H, halogen, linear orbranched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy,C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl, C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy,C₇-C₁₂-arylalkoxy, C₉-C₁₅-alkenylarylalkoxy, nitro-,C₆-C₁₂-arylsulfonyl, 4-alkylarylsulfonyl, C₁-C₂₀-alkylcarboxy,C₁-C₈-alkoxycarbonyl, SR₁₂, NHR₁₂ or NR₁₂R₁₃ with R₁₂ and R₁₃ beingindependently selected from H, linear or branched C₁-C₂₀-alkyl, linearor branched C₂-C₈-alkenyl and C₃-C₈-cycloalkyl, and an O-, S- orN-containing 5- or 6-membered heterocyclic ring; R₆ is OSiR₁₄R₁₅R₁₆ withR₁₄, R₁₅ and R₁₆ being independently selected from linear or branchedC₁-C₂₀-alkyl or C₆-C₁₂-aryl, obtained by a process, as defined herein,is provided.

According to another aspect of the present invention, abis(acyl)phosphinic acid of the general formula III,

wherein R₁, R₂, R₃, R₄, R₅, R₇, R₈, R₉, R₁₀ and R₁₁ are the same ordifferent and are independently selected from H, halogen, linear orbranched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy,C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl, C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy,C₇-C₁₂-arylalkoxy, C₉-C₁₅-alkenylarylalkoxy, nitro-,C₆-C₁₂-arylsulfonyl, 4-alkylarylsulfonyl, C₁-C₂₀-alkylcarboxy,C₁-C₈-alkoxycarbonyl, SR₁₂, NHR₁₂ or NR₁₂R₁₃ with R₁₂ and R₁₃ beingindependently selected from H, linear or branched C₁-C₂₀-alkyl, linearor branched C₂-C₈-alkenyl and C₃-C₈-cycloalkyl, and an O-, S- orN-containing 5- or 6-membered heterocyclic ring; R₆ is OH, obtained by aprocess, as defined herein, is provided.

In the following, the details and preferred embodiments of the inventiveprocess for the preparation of the bis(acyl)phosphinic acid silyl esterof the general formula I as well as the bis(acyl)phosphinic acid of thegeneral formula II will be described in more detail. It is to beunderstood that these technical details and embodiments also apply tothe inventive products, as far as applicable.

DETAILED DESCRIPTION OF THE INVENTION

A process for the preparation of a bis(acyl)phosphinic acid silyl esterof the general formula I is provided. It is appreciated that abis(acyl)phosphinic acid silyl ester of the general formula I isprepared,

wherein R₁, R₂, R₃, R₄, R₅, R₇, R₈, R₉, R₁₀ and R₁₁ are the same ordifferent and are independently selected from H, halogen, linear orbranched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy,C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl, C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy,C₇-C₁₂-arylalkoxy, C₉-C₁₅-alkenylarylalkoxy, nitro-,C₆-C₁₂-arylsulfonyl, 4-alkylarylsulfonyl, C₁-C₂₀-alkylcarboxy,C₁-C₈-alkoxycarbonyl, SR₁₂, NHR₁₂ or NR₁₂R₁₃ with R₁₂ and R₁₃ beingindependently selected from H, linear or branched C₁-C₂₀-alkyl, linearor branched C₂-C₈-alkenyl and C₃-C₈-cycloalkyl, and an O-, S- orN-containing 5- or 6-membered heterocyclic ring; R₆ is OSiR₁₄R₁₅R₁₆ withR₁₄, R₁₅ and R₁₆ being independently selected from linear or branchedC₁-C₂₀-alkyl or C₆-C₁₂-aryl.

As regards R₁, R₂, R₃, R₄ and R₅ in the general formula I, it is to benoted that they can be the same or different. Preferably, R₁, R₂, R₃, R₄and R₅ are the same or different and are independently selected from H,halogen, linear or branched C₁-C₂₀-alkyl, linear or branchedC₂-C₈-alkenyl, C₁-C₈-alkoxy, C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl,C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy, C₇-C₁₂-arylalkoxy,C₉-C₁₅-alkenylarylalkoxy, nitro-, C₆-C₁₂-arylsulfonyl,4-alkylarylsulfonyl, C₁-C₂₀-alkylcarboxy, C₁-C₈-alkoxycarbonyl, SR₁₂,NHR₁₂ or NR₁₂R₁₃ with R₁₂ and R₁₃ being independently selected from H,linear or branched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl andC₃-C₈-cycloalkyl, and an O-, S- or N-containing 5- or 6-memberedheterocyclic ring.

The term “linear or branched C₁-C₂₀-alkyl” in the meaning of the presentinvention refers to a linear or branched chain alkyl group having 1 to20 carbon atoms, and includes, for example, methyl, ethyl, propyl,isopropyl, n-butyl, isobutyl, sec. butyl, tert. butyl, n-pentyl,isopentyl, neopentyl, hexyl, heptyl, octyl, 2-ethylhexyl,1,1,3,3-tetramethylbutyl, n-heptyl, 2,4,4 trimethylpentyl, 2-ethylhexyl,octyl, nonyl, decyl, undecyl, dodecyl, tetradecyl, pentadecyl,hexadecyl, heptadecyl, octadecyl, nonadecyl and eicosyl.

The term “linear or branched C₂-C₈-alkenyl” in the meaning of thepresent invention refers to a linear or branched chain alkenyl grouphaving 2 to 8 carbon atoms, and includes, for example, ethenyl,propenyl, butenyl, triisobutenyl, pentenyl, hexenyl, heptenyl andoctenyl, preferably ethenyl or propenyl. The term “alkenyl” in themeaning of the present invention includes the cis and trans isomers.

The term “C₁-C₈-alkoxy” in the meaning of the present invention meansthat the alkoxy moiety has a linear or branched chain alkyl having 1 to8 carbon atoms, and includes, for example, methoxy, ethoxy, propoxy,isopropoxy, butoxy, isobutoxy, tertiary butoxy, pentyloxy, hexyloxy,heptyloxy and octyloxy.

The term “C₂-C₈-alkenyloxy” in the meaning of the present inventionmeans that the alkenyloxy moiety has a linear or branched chain alkenylhaving 2 to 8 carbon atoms, and includes, for example, ethenyloxy,propenyloxy, butenyloxy, triisobutenyloxy, pentenyloxy, hexenyloxy,heptenyloxy and octenyloxy.

The term “C₃-C₈-cycloalkyl” in the meaning of the present inventionrefers to a cyclic alkyl having 3 to 8 carbon atoms, and includes, forexample, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, andcycloheptyl, preferably cyclopentyl and cyclohexyl.

The term “C₆-C₁₂-aryl” in the meaning of the present invention refers toa group containing one or more 6-membered unsaturated hydrocarbonring(s), wherein the unsaturation is represented formally by conjugateddouble bonds and which may optionally be substituted at one or morecarbon atoms of such ring(s) by independently selected alkyl groups, andincludes, for example, phenyl, naphthyl, methylphenyl, dimethoxyphenyl,5-isopropyl-2-methylphenyl, methylphenyl and t-butylphenyl, preferablynaphthyl.

The term “C₃-C₈-cycloalkoxy” in the meaning of the present inventionmeans that the cycloalkoxy moiety has a cyclic alkyl having 3 to 8carbon atoms, and includes, for example, cyclopropyloxy, cyclobutyloxy,cyclopentyloxy, cyclohexyloxy, and cycloheptyloxy, preferablycyclopentyloxy and cyclohexyloxy.

The term “C₇-C₁₂-arylalkoxy” in the meaning of the present inventionmeans that the alkoxy moiety has a linear or branched chain alkyl having1 to 8 carbon atoms, preferably 1 or 2 carbon atoms, which is connectedto C₆-C₁₂-aryl.

The term “C₉-C₁₅-alkenylarylalkoxy” in the meaning of the presentinvention means that the alkoxy moiety has a linear or branched chainalkyl having 1 to 8 carbon atoms, preferably 1 or 2 carbon atoms, whichis connected to C₆-C₁₂-aryl, preferably C₆-aryl, which is furtherconnected to linear or branched C₂-C₈-alkenyl, preferably C₂-alkenyl.Preferably, the alkoxy and alkenyl moieties are connected inpara-position of the aryl moiety.

The term “C₆-C₁₂-arylsulfonyl” in the meaning of the present inventionrefers to a sulfonyl moiety having a C₆-C₁₂-aryl.

The term “4-alkylarylsulfonyl” in the meaning of the present inventionrefers to a sulfonyl moiety having a C₆-C₁₂-aryl, which is connected toa linear or branched C₁-C₂₀-alkyl. The alkyl moiety is connected inpara-position of the aryl moiety.

The term “halogen” in the meaning of the present invention refers tochloro, bromo or iodo.

Preferably, R₁, R₂, R₃, R₄ and R₅ are the same or different and areindependently selected from H, halogen, linear or branched C₁-C₂₀-alkyl,linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy, C₂-C₈-alkenyloxy,C₃-C₈-cycloalkyl, C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy, C₇-C₁₂-arylalkoxy,C₉-C₁₅-alkenylarylalkoxy, nitro-, C₆-C₁₂-arylsulfonyl,4-alkylarylsulfonyl, C₁-C₂₀-alkylcarboxy, C₁-C₈-alkoxycarbonyl and anO-, S- or N-containing 5- or 6-membered heterocyclic ring.

In one embodiment, R₁, R₂, R₃, R₄ and R₅ in the general formula I arethe same or different and are independently selected from H, halogen,linear or branched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl,C₁-C₈-alkoxy, C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl and C₆-C₁₂-aryl.Preferably, R₁, R₂, R₃, R₄ and R₅ are the same or different and areindependently selected from H, halogen and, linear or branchedC₁-C₂₀-alkyl. Most preferably, R₁, R₂, R₃, R₄ and R₅ are the same ordifferent and are independently selected from H and, linear or branchedC₁-C₂₀-alkyl.

Thus, it is preferred that one or more of R₁, R₂, R₃, R₄ and R₅ is/areH.

Additionally or alternatively, it is preferred that one or more of R₁,R₂, R₃, R₄ and R₅ is/are linear or branched C₁-C₂₀-alkyl, preferablylinear or branched C₁-C₁₈-alkyl, more preferably linear or branchedC₁-C₁₂-alkyl and most preferably linear C₁-C₈-alkyl, e.g. linearC₁-C₈-alkyl. For example, one or more of R₁, R₂, R₃, R₄ and R₅ is/arelinear or branched C₁-C₆-alkyl, e.g. linear C₁-C₆-alkyl, preferablylinear or branched C₁-C₄-alkyl, e.g. linear C₁-C₄-alkyl, and mostpreferably linear or branched C₁-C₃-alkyl, e.g. linear C₁-C₃-alkyl. Itis especially preferred that one or more of R₁, R₂, R₃, R₄ and R₅ is/areC₁- or C₂-alkyl, e.g. C₁-alkyl.

Preferably, R₁, R₃ and R₅ are the same. In this embodiment, R₁, R₃ andR₅ are preferably selected from H, halogen, linear or branchedC₁-C₈-alkyl, linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy,C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl, C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy,C₇-C₁₂-arylalkoxy, C₉-C₁₅-alkenylarylalkoxy, nitro-,C₆-C₁₂-arylsulfonyl, 4-alkylarylsulfonyl, C₁-C₂₀-alkylcarboxy,C₁-C₈-alkoxycarbonyl, SR₁₂, NHR₁₂ or NR₁₂R₁₃ with R₁₂ and R₁₃ beingindependently selected from H, linear or branched C₁-C₂₀-alkyl, linearor branched C₂-C₈-alkenyl and C₃-C₈-cycloalkyl, and an O-, S- orN-containing 5- or 6-membered heterocyclic ring. For example, R₁, R₃ andR₅ are the same and are selected from linear or branched C₁-C₈-alkyl,linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy, C₂-C₈-alkenyloxy,C₃-C₈-cycloalkyl and an O-, S- or N-containing 5- or 6-memberedheterocyclic ring.

In one embodiment, R₁, R₃ and R₅ are the same and are linear or branchedC₁-C₂₀-alkyl, preferably linear or branched C₁-C₁₈-alkyl, morepreferably linear or branched C₁-C₁₂-alkyl and most preferably linearC₁-C₈-alkyl, e.g. linear C₁-C₈-alkyl. For example, R₁, R₃ and R₅ are thesame and are linear or branched C₁-C₆-alkyl, e.g. linear C₁-C₆-alkyl,preferably linear or branched C₁-C₄-alkyl, e.g. linear C₁-C₄-alkyl, andmost preferably linear or branched C₁-C₃-alkyl, e.g. linear C₁-C₃-alkyl.It is especially preferred that R₁, R₃ and R₅ are the same and are C₁-or C₂-alkyl, e.g. C₁-alkyl.

In one embodiment, R₁, R₃ and R₅ are the same and are SR₁₂, NHR₁₂ orNR₁₂R₁₃ with R₁₂ and R₁₃ being independently selected from H, linear orbranched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl andC₃-C₈-cycloalkyl.

In one embodiment, R₂ and R₄ are the same. In this embodiment, R₂ and R₄are preferably selected from H, halogen, linear or branchedC₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy,C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl, C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy,C₇-C₁₂-arylalkoxy, C₉-C₁₅-alkenylarylalkoxy, nitro-,C₆-C₁₂-arylsulfonyl, 4-alkylarylsulfonyl, C₁-C₂₀-alkylcarboxy,C₁-C₈-alkoxycarbonyl, SR₁₂, NHR₁₂ or NR₁₂R₁₃ with R₁₂ and R₁₃ beingindependently selected from H, linear or branched C₁-C₂₀-alkyl, linearor branched C₂-C₈-alkenyl and C₃-C₈-cycloalkyl, and an O-, S- orN-containing 5- or 6-membered heterocyclic ring. Preferably, R₂ and R₄are selected from H, halogen, linear or branched C₁-C₂₀-alkyl, linear orbranched C₂-C₈-alkenyl, C₁-C₈-alkoxy, C₂-C₈-alkenyloxy,C₃-C₈-cycloalkyl, C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy, C₇-C₁₂-arylalkoxy,C₉-C₁₅-alkenylarylalkoxy and an O-, S- or N-containing 5- or 6-memberedheterocyclic ring. For example, R₂ and R₄ are the same and are selectedfrom H, linear or branched C₁-C₂₀-alkyl, linear or branchedC₂-C₈-alkenyl, C₁-C₈-alkoxy, C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl and anO-, S- or N-containing 5- or 6-membered heterocyclic ring.

In one embodiment, R₂ and R₄ are the same and are H.

It is appreciated that R₂ and R₄ are preferably different from R₁, R₃and R₅. Thus, if R₂ and R₄ are different from R₁, R₃, and R₅, R₂ and R₄are preferably the same and are H and R₁, R₃ and R₅ are the same and arelinear or branched C₁-C₂₀-alkyl, preferably linear or branchedC₁-C₁₈-alkyl, more preferably linear or branched C₁-C₁₂-alkyl and mostpreferably linear C₁-C₈-alkyl, e.g. linear C₁-C₈-alkyl. For example, R₂and R₄ are the same and are H and R₁, R₃ and R₅ are the same and arelinear or branched C₁-C₆-alkyl, e.g. linear C₁-C₆-alkyl, preferablylinear or branched C₁-C₄-alkyl, e.g. linear C₁-C₄-alkyl, and mostpreferably linear or branched C₁-C₃-alkyl, e.g. linear C₁-C₃-alkyl. Itis especially preferred that R₂ and R₄ are the same and are H and R₁, R₃and R₅ are the same and are C₁- or C₂-alkyl, e.g. C₁-alkyl.

In one embodiment, R₂ and R₄ are the same and are H and R₁, R₃ and R₅are the same and are SR₁₂, NHR₁₂ or NR₁₂R₁₃ with R₁₂ and R₁₃ beingindependently selected from H, linear or branched C₁-C₂₀-alkyl, linearor branched C₂-C₈-alkenyl and C₃-C₈-cycloalkyl.

As regards R₇, R₈, R₉, R₁₀ and R₁₁ in the general formula I, it is to benoted that they can be the same or different. Preferably, R₇, R₈, R₉,R₁₀ and R₁₁ are the same or different and are independently selectedfrom H, halogen, linear or branched C₁-C₂₀-alkyl, linear or branchedC₂-C₈-alkenyl, C₁-C₈-alkoxy, C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl,C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy, C₇-C₁₂-arylalkoxy,C₉-C₁₅-alkenylarylalkoxy, nitro-, C₆-C₁₂-arylsulfonyl,4-alkylarylsulfonyl, C₁-C₂₀-alkylcarboxy, C₁-C₈-alkoxycarbonyl, SR₁₂,NHR₁₂ or NR₁₂R₁₃ with R₁₂ and R₁₃ being independently selected from H,linear or branched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl andC₃-C₈-cycloalkyl, and an O-, S- or N-containing 5- or 6-memberedheterocyclic ring. More preferably, R₇, R₈, R₉, R₁₀ and R₁₁ are the sameor different and are independently selected from H, halogen, linear orbranched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy,C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl, C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy,C₇-C₁₂-arylalkoxy, C₉-C₁₅-alkenylarylalkoxy and an O-, S- orN-containing 5- or 6-membered heterocyclic ring.

In one embodiment, R₇, R₈, R₉, R₁₀ and R₁₁ in the general formula I arethe same or different and are independently selected from H, halogen,linear or branched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl,C₁-C₈-alkoxy, C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl and C₆-C₁₂-aryl.Preferably, R₇, R₈, R₉, R₁₀ and R₁₁ are the same or different and areindependently selected from H, halogen and, linear or branchedC₁-C₂₀-alkyl. Most preferably, R₇, R₈, R₉, R₁₀ and R₁₁ are the same ordifferent and are independently selected from H and, linear or branchedC₁-C₂₀-alkyl.

Thus, it is preferred that one or more of R₇, R₈, R₉, R₁₀ and R₁₁ is/areH.

Additionally or alternatively, it is preferred that one or more of R₇,R₈, R₉, R₁₀ and R₁₁ is/are linear or branched C₁-C₂₀-alkyl, preferablylinear or branched C₁-C₁₈-alkyl, more preferably linear or branchedC₁-C₁₂-alkyl and most preferably linear C₁-C₈-alkyl, e.g. linearC₁-C₈-alkyl. For example, one or more of R₇, R₈, R₉, R₁₀ and R₁₁ is/arelinear or branched C₁-C₆-alkyl, e.g. linear C₁-C₆-alkyl, preferablylinear or branched C₁-C₄-alkyl, e.g. linear C₁-C₄-alkyl, and mostpreferably linear or branched C₁-C₃-alkyl, e.g. linear C₁-C₃-alkyl. Itis especially preferred that one or more of R₇, R₈, R₉, R₁₀ and R₁₁is/are C₁- or C₂-alkyl, e.g. C₁-alkyl.

Preferably, R₇, R₉ and R₁₁ are the same. In this embodiment, R₇, R₉ andR₁₁ are preferably selected from H, halogen, linear or branchedC₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy,C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl, C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy,C₇-C₁₂-arylalkoxy, C₉-C₁₅-alkenylarylalkoxy, nitro-,C₆-C₁₂-arylsulfonyl, 4-alkylarylsulfonyl, C₁-C₂₀-alkylcarboxy,C₁-C₈-alkoxycarbonyl, SR₁₂, NHR₁₂ or NR₁₂R₁₃ with R₁₂ and R₁₃ beingindependently selected from H, linear or branched C₁-C₂₀-alkyl, linearor branched C₂-C₈-alkenyl and C₃-C₈-cycloalkyl, and an O-, S- orN-containing 5- or 6-membered heterocyclic ring. Preferably, R₇, R₉ andR₁₁ are selected from H, halogen, linear or branched C₁-C₂₀-alkyl,linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy, C₂-C₈-alkenyloxy,C₃-C₈-cycloalkyl, C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy, C₇-C₁₂-arylalkoxy,C₉-C₁₅-alkenylarylalkoxy and an O-, S- or N-containing 5- or 6-memberedheterocyclic ring. For example, R₇, R₉ and R₁₁ are the same and areselected from linear or branched C₁-C₂₀-alkyl, linear or branchedC₂-C₈-alkenyl, C₁-C₈-alkoxy, C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl and anO-, S- or N-containing 5- or 6-membered heterocyclic ring.

In one embodiment, R₇, R₉ and R₁₁ are the same and are linear orbranched C₁-C₂₀-alkyl, preferably linear or branched C₁-C₁₈-alkyl, morepreferably linear or branched C₁-C₁₂-alkyl and most preferably linearC₁-C₈-alkyl, e.g. linear C₁-C₈-alkyl. For example, R₇, R₉ and R₁₁ arethe same and are linear or branched C₁-C₆-alkyl, e.g. linearC₁-C₆-alkyl, preferably linear or branched C₁-C₄-alkyl, e.g. linearC₁-C₄-alkyl, and most preferably linear or branched C₁-C₃-alkyl, e.g.linear C₁-C₃-alkyl. It is especially preferred that R₇, R₉ and R₁₁ arethe same and are C₁- or C₂-alkyl, e.g. C₁-alkyl.

In one embodiment, R₇, R₉ and R₁₁ are the same and are SR₁₂, NHR₁₂ orNR₁₂R₁₃ with R₁₂ and R₁₃ being independently selected from H, linear orbranched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl andC₃-C₈-cycloalkyl.

In one embodiment, R₈ and R₁₀ are the same. In this embodiment, R₈ andR₁₀ are preferably selected from H, halogen, linear or branchedC₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy,C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl, C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy,C₇-C₁₂-arylalkoxy, C₉-C₁₅-alkenylarylalkoxy, nitro-,C₆-C₁₂-arylsulfonyl, 4-alkylarylsulfonyl, C₁-C₂₀-alkylcarboxy,C₁-C₈-alkoxycarbonyl, SR₁₂, NHR₁₂ or NR₁₂R₁₃ with R₁₂ and R₁₃ beingindependently selected from H, linear or branched C₁-C₂₀-alkyl, linearor branched C₂-C₈-alkenyl and C₃-C₈-cycloalkyl, and an O-, S- orN-containing 5- or 6-membered heterocyclic ring. Preferably, R₈ and R₁₀are selected from H, halogen, linear or branched C₁-C₂₀-alkyl, linear orbranched C₂-C₈-alkenyl, C₁-C₈-alkoxy, C₂-C₈-alkenyloxy,C₃-C₈-cycloalkyl, C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy, C₇-C₁₂-arylalkoxy,C₉-C₁₅-alkenylarylalkoxy and an O-, S- or N-containing 5- or 6-memberedheterocyclic ring. For example, R₈ and R₁₀ are the same and are selectedfrom H, linear or branched C₁-C₂₀-alkyl, linear or branchedC₂-C₈-alkenyl, C₁-C₈-alkoxy, C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl and anO-, S- or N-containing 5- or 6-membered heterocyclic ring.

In one embodiment, R₈ and R₁₀ are the same and are H.

It is appreciated that R₈ and R₁₀ are preferably different from R₇, R₉and R₁₁. Thus, if R₈ and R₁₀ are different from R₇, R₉ and R₁₁, R₈ andR₁₀ are preferably the same and are H and R₇, R₉ and R₁₁ are the sameand are linear or branched C₁-C₂₀-alkyl, preferably linear or branchedC₁-C₁₈-alkyl, more preferably linear or branched C₁-C₁₂-alkyl and mostpreferably linear C₁-C₈-alkyl, e.g. linear C₁-C₈-alkyl. For example, R₈and R₁₀ are the same and are H and R₇, R₉ and R₁₁ are the same and arelinear or branched C₁-C₆-alkyl, e.g. linear C₁-C₆-alkyl, preferablylinear or branched C₁-C₄-alkyl, e.g. linear C₁-C₄-alkyl, and mostpreferably linear or branched C₁-C₃-alkyl, e.g. linear C₁-C₃-alkyl. Itis especially preferred that R₈ and R₁₀ are the same and are H and R₇,R₉ and R₁₁ are the same and are C₁- or C₂-alkyl, e.g. C₁-alkyl.

In one embodiment, R₈ and R₁₀ are the same and are H and R₇, R₉ and R₁₁are the same and are SR₁₂, NHR₁₂ or NR₁₂R₁₃ with R₁₂ and R₁₃ beingindependently selected from H, linear or branched C₁-C₂₀-alkyl, linearor branched C₂-C₈-alkenyl and C₃-C₈-cycloalkyl.

As regards R₁, R₂, R₃, R₄, R₅, R₇, R₈, R₉, R₁₀ and R₁₁ in generalformula I, it is to be noted that they can be the same or different.Preferably, R₁, R₂, R₃, R₄, R₅, R₇, R₈, R₉, R₁₀ and R₁₁ are the same ordifferent and are independently selected from H, halogen, linear orbranched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy,C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl, C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy,C₇-C₁₂-arylalkoxy, C₉-C₁₅-alkenylarylalkoxy, nitro-,C₆-C₁₂-arylsulfonyl, 4-alkylarylsulfonyl, C₁-C₂₀-alkylcarboxy,C₁-C₈-alkoxycarbonyl, SR₁₂, NHR₁₂ or NR₁₂R₁₃ with R₁₂ and R₁₃ beingindependently selected from H, linear or branched C₁-C₂₀-alkyl, linearor branched C₂-C₈-alkenyl and C₃-C₈-cycloalkyl, and an O-, S- orN-containing 5- or 6-membered heterocyclic ring.

In one embodiment, R₁, R₂, R₃, R₄, R₅, R₇, R₈, R₉, R₁₀ and R₁₁ in thegeneral formula I are the same or different and are independentlyselected from H, halogen, linear or branched C₁-C₂₀-alkyl, linear orbranched C₂-C₈-alkenyl, C₁-C₈-alkoxy, C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyland C₆-C₁₂-aryl. Preferably, R₁, R₂, R₃, R₄, R₅, R₇, R₈, R₉, R₁₀ and R₁₁are the same or different and are independently selected from H, halogenand, linear or branched C₁-C₂₀-alkyl. Most preferably, R₁, R₂, R₃, R₄,R₅, R₇, R₈, R₉, R₁₀ and R₁₁ are the same or different and areindependently selected from H and, linear or branched C₁-C₂₀-alkyl.

In one embodiment, R₁, R₂, R₃, R₄, R₅, R₇, R₈, R₉, R₁₀ and R₁₁ ingeneral formula I are the same. In this embodiment, R₁, R₂, R₃, R₄, R₅,R₇, R₈, R₉, R₁₀ and R₁₁ are preferably H.

Alternatively, R₁, R₂, R₃, R₄, R₅, R₇, R₈, R₉, R₁₀ and R₁₁ in generalformula I are different.

It is preferred that one or more of R₁, R₂, R₃, R₄, R₅, R₇, R₈, R₉, R₁₀and R₁₁ in general formula I is/are H.

Additionally or alternatively, it is preferred that one or more of R₁,R₂, R₃, R₄, R₅, R₇, R₈, R₉, R₁₀ and R₁₁ in general formula I is/arelinear or branched C₁-C₂₀-alkyl, preferably linear or branchedC₁-C₁₈-alkyl, more preferably linear or branched C₁-C₁₂-alkyl and mostpreferably linear C₁-C₈-alkyl, e.g. linear C₁-C₈-alkyl. For example, oneor more of R₁, R₂, R₃, R₄, R₅, R₇, R₈, R₉, R₁₀ and R₁₁ is/are linear orbranched C₁-C₆-alkyl, e.g. linear C₁-C₆-alkyl, preferably linear orbranched C₁-C₄-alkyl, e.g. linear C₁-C₄-alkyl, and most preferablylinear or branched C₁-C₃-alkyl, e.g. linear C₁-C₃-alkyl. It isespecially preferred that one or more of R₁, R₂, R₃, R₄, R₅, R₇, R₈, R₉,R₁₀ and R₁₁ in general formula I is/are C₁- or C₂-alkyl, e.g. C₁-alkyl.

Preferably, R₁, R₃, R₅, R₇, R₉ and R₁₁ in general formula I are thesame. In this embodiment, R₁, R₃, R₅, R₇, R₉ and R₁₁ are selected fromH, halogen, linear or branched C₁-C₂₀-alkyl, linear or branchedC₂-C₈-alkenyl, C₁-C₈-alkoxy, C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl,C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy, C₇-C₁₂-arylalkoxy,C₉-C₁₅-alkenylarylalkoxy, nitro-, C₆-C₁₂-arylsulfonyl,4-alkylarylsulfonyl, C₁-C₂₀-alkylcarboxy, C₁-C₈-alkoxycarbonyl, SR₁₂,NHR₁₂ or NR₁₂R₁₃ with R₁₂ and R₁₃ being independently selected from H,linear or branched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl andC₃-C₈-cycloalkyl, and an O-, S- or N-containing 5- or 6-memberedheterocyclic ring. Preferably, R₁, R₃, R₅, R₇, R₉ and R₁₁ are the sameand are selected from H, halogen, linear or branched C₁-C₂₀-alkyl,linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy, C₂-C₈-alkenyloxy,C₃-C₈-cycloalkyl, C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy, C₇-C₁₂-arylalkoxy,C₉-C₁₅-alkenylarylalkoxy, and an O-, S- or N-containing 5- or 6-memberedheterocyclic ring. For example, R₁, R₃, R₅, R₇, R₉ and R₁₁ are the sameand are selected from linear or branched C₁-C₂₀-alkyl, linear orbranched C₂-C₈-alkenyl, C₁-C₈-alkoxy, C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyland an O-, S- or N-containing 5- or 6-membered heterocyclic ring.

In one embodiment, R₁, R₃, R₅, R₇, R₉ and R₁₁ in general formula I arethe same and are linear or branched C₁-C₂₀-alkyl, preferably linear orbranched C₁-C₁₈-alkyl, more preferably linear or branched C₁-C₁₂-alkyland most preferably linear C₁-C₈-alkyl, e.g. linear C₁-C₈-alkyl. Forexample, R₁, R₃, R₅, R₇, R₉ and R₁₁ are the same and are linear orbranched C₁-C₆-alkyl, e.g. linear C₁-C₆-alkyl, preferably linear orbranched C₁-C₄-alkyl, e.g. linear C₁-C₄-alkyl, and most preferablylinear or branched C₁-C₃-alkyl, e.g. linear C₁-C₃-alkyl. It isespecially preferred that R₁, R₃, R₅, R₇, R₉ and R₁₁ are the same andare C₁- or C₂-alkyl, e.g. C₁-alkyl.

In one embodiment, R₂, R₄, R₈ and R₁₀ in general formula I are the same.In this embodiment, R₂, R₄, R₈ and R₁₀ are selected from H, halogen,linear or branched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl,C₁-C₈-alkoxy, C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl, C₆-C₁₂-aryl,C₃-C₈-cycloalkoxy, C₇-C₁₂-arylalkoxy, C₉-C₁₅-alkenylarylalkoxy, nitro-,C₆-C₁₂-arylsulfonyl, 4-alkylarylsulfonyl, C₁-C₂₀-alkylcarboxy,C₁-C₈-alkoxycarbonyl, SR₁₂, NHR₁₂ or NR₁₂R₁₃ with R₁₂ and R₁₃ beingindependently selected from H, linear or branched C₁-C₂₀-alkyl, linearor branched C₂-C₈-alkenyl and C₃-C₈-cycloalkyl, and an O-, S- orN-containing 5- or 6-membered heterocyclic ring. Preferably, R₂, R₄, R₈and R₁₀ are selected from H, halogen, linear or branched C₁-C₂₀-alkyl,linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy, C₂-C₈-alkenyloxy,C₃-C₈-cycloalkyl, C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy, C₇-C₁₂-arylalkoxy,C₉-C₁₅-alkenylarylalkoxy and an O-, S- or N-containing 5- or 6-memberedheterocyclic ring. For example, R₂, R₄, R₈ and R₁₀ are the same and areselected from H, linear or branched C₁-C₂₀-alkyl, linear or branchedC₂-C₈-alkenyl, C₁-C₈-alkoxy, C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl and anO-, S- or N-containing 5- or 6-membered heterocyclic ring.

In one embodiment, R₂, R₄, R₈ and R₁₀ are the same and are H.

It is appreciated that R₂, R₄, R₈ and R₁₀ are preferably different fromR₁, R₃, R₅, R₇, R₉ and R₁₁. Thus, if R₂, R₄, R₈ and R₁₀ are differentfrom R₁, R₃, R₅, R₇, R₉ and R₁₁, R₂, R₄, R₈ and R₁₀ are preferably thesame and are H and R₁, R₃, R₅, R₇, R₉ and R₁₁ are the same and arelinear or branched C₁-C₂₀-alkyl, preferably linear or branchedC₁-C₁₈-alkyl, more preferably linear or branched C₁-C₁₂-alkyl and mostpreferably linear C₁-C₈-alkyl, e.g. linear C₁-C₈-alkyl. For example, R₂,R₄, R₈ and R₁₀ are the same and are H and R₁, R₃, R₅, R₇, R₉ and R₁₁ arethe same and are linear or branched C₁-C₆-alkyl, e.g. linearC₁-C₆-alkyl, preferably linear or branched C₁-C₄-alkyl, e.g. linearC₁-C₄-alkyl, and most preferably linear or branched C₁-C₃-alkyl, e.g.linear C₁-C₃-alkyl. It is especially preferred that R₂, R₄, R₈ and R₁₀are the same and are H and R₁, R₃, R₅, R₇, R₉ and R₁₁ are the same andare C₁- or C₂-alkyl, e.g. C₁-alkyl.

In one embodiment, the bis(acyl)phosphinic acid silyl ester of thegeneral formula I is a bis(acyl)phosphinic acid silyl ester, in whichR₁, R₃, R₅, R₇, R₉ and R₁₁ in general formula I are the same and R₂, R₄,R₈ and R₁₀ are the same. Preferably, R₁, R₃, R₅, R₇, R₉ and R₁₁ ingeneral formula I are the same and are C₁-alkyl and R₂, R₄, R₈ and R₁₀are the same and are H. Alternatively, R₁, R₃, R₅, R₇, R₉ and R₁₁ ingeneral formula I are the same and are H and R₂, R₄, R₈ and R₁₀ are thesame and are C₁-alkoxy. Alternatively, R₁, R₃, R₅, R₇, R₉ and R₁₁ ingeneral formula I are the same and are H and R₂, R₄, R₈ and R₁₀ are thesame and are chloro.

Alternatively, the bis(acyl)phosphinic acid silyl ester of the generalformula I is a bis(acyl)phosphinic acid silyl ester, in which R₁, R₃ andR₅ in general formula I are the same, R₇, R₉ and R₁₁ are the same, R₂and R₄ are the same and R₈ and R₁₀ are the same. In this embodiment, R₁,R₃ and R₅ in general formula I are different from R₇, R₉ and R₁₁ and R₂and R₄ are different from R₈ and R₁₀. It is thus appreciated that amixed bis(acyl)phosphinic acid silyl ester of the general formula I canbe prepared by the process of the present invention.

It is appreciated that R₆ in the general formula I is OSiR₁₄R₁₅R₁₆ withR₁₄, R₁₅ and R₁₆ being independently selected from linear or branchedC₁-C₂₀-alkyl or C₆-C₁₂-aryl. It is appreciated that R₁₄, R₁₅ and R₁₆ canbe the same or different. Preferably, R₁₄, R₁₅ and R₁₆ are the same, Forexample, R₁₄, R₁₅ and R₁₆ are the same and are linear or branchedC₁-C₂₀-alkyl, preferably linear or branched C₁-C₁₈-alkyl, morepreferably linear or branched C₁-C₁₂-alkyl and most preferably linearC₁-C₈-alkyl, e.g. linear C₁-C₈-alkyl. Preferably, R₁₄, R₁₅ and R₁₆ arethe same and are linear or branched C₁-C₆-alkyl, e.g. linearC₁-C₆-alkyl, preferably linear or branched C₁-C₄-alkyl, e.g. linearC₁-C₄-alkyl, and most preferably linear or branched C₁-C₃-alkyl, e.g.linear C₁-C₃-alkyl. It is especially preferred that R₁₄, R₁₅ and R₁₆ arethe same and are C₁- or C₂-alkyl, e.g. C₁-alkyl.

Alternatively, R₁₄, R₁₅ and R₁₆ are the same and are phenyl ormethylphenyl, preferably phenyl.

In one embodiment, R₆ in the general formula I is OSiR₁₄R₁₅R₁₆ with R₁₄,R₁₅ and R₁₆ being C₁- or C₂-alkyl, e.g. C₁-alkyl. That is to say, R₆ inthe general formula I is preferably trimethylsilyloxy.

Thus, it is appreciated that the process of the present inventionresults in the preparation of the bis(acyl)phosphinic acid silyl esterof the general formula I.

It is appreciated that the bis(acyl)phosphinic acid silyl ester of thegeneral formula I is prepared by a specific process, namely a processallowing the easy preparation of an intermediate product suitable forthe conversion into bis(acyl)phosphinic acids.

In particular, the process is characterized in that it comprises thesteps of

-   -   a) heating ammonium hypophosphite with a silylating agent for        obtaining a bis(silyl ether)phosphine, and    -   b) reacting the bis(silyl ether)phosphine obtained in step a)        with a compound of the general formula IIa and/or IIb,

-   -   wherein R₁, R₂, R₃, R₄ and R₅ and/or R₇, R₈, R₉, R₁₀ and R₁₁ are        as defined above; Z is halogen.

Accordingly, in a first step ammonium hypophosphite is heated with asilylating agent. It is to be noted that this step preferably results inthe quantitative reaction of the starting materials to the correspondingbis(silyl ether)phosphine. Thus, very high yields and purities and veryhigh conversions are achieved within a few hours, and thus this stepadvantageously provides a bis(silyl ether)phosphine with high purity forthe following process step b).

The silylating agent can be every silylating agent well known in theart. However, in order to obtain advantageous yields in the furtherprocess, the silylating agent is preferably a compound of the generalformula Va and/or VbA-SiR₁₄R₁₅R₁₆  Va,

wherein R₁₄, R₁₅ and R₁₆ are the same or different and are independentlyselected from linear or branched C₁-C₂₀-alkyl or C₆-C₁₂-aryl, and A isselected from halogen, triflate (OSO₂CF₃), cyanide, azide and1-imidazolyl.R₁₆R₁₅R₁₄Si—B—SiR₁₄R₁₅R₁₆  Vb,

wherein R₁₄, R₁₅ and R₁₆ are the same or different and are independentlyselected from linear or branched C₁-C₂₀-alkyl or C₆-C₁₂-aryl, and B isselected from O, NH, NCH₃, OC(CH₃)═N, OC(CF₃)═N, NH(C═O)NH, andNH(C═O)O.

With regard to the definition of the R₁₄, R₁₅ and R₁₆ in general formulaVa and/or Vb and preferred embodiments thereof, reference is also madeto the statements provided above when discussing the technical detailsof the bis(acyl)phosphinic acid silyl ester of the general formula I,and especially R₆, obtained by the process of the present invention.

Preferably, the silylating agent is selected from the group comprisinghexamethyldisilazane, trimethylsilyl chloride, trimethylsilyl bromide,trimethylsilyl iodide, triethylsilyl chloride, triethylsilyl bromide,tri-n-propylsilyl chloride, triisopropylsilyl chloride,t-butyldimethylsilyl chloride, bis(trimethylsilyl)acetamide,N,N-bis(trimethylsilyl)methylamine, and mixtures thereof. Morepreferably, the silylating agent is selected from the group comprisinghexamethyldisilazane, N,N-bis(trimethylsilyl)methylamine, trimethylsilylchloride and mixtures thereof. Most preferably, the silylating agent ishexamethyldisilazane and/or trimethylsilyl chloride. For example, thesilylating agent is hexamethyldisilazane or trimethylsilyl chloride,preferably hexamethyldisilazane. Alternatively, the silylating agent isa mixture of hexamethyldisilazane and trimethylsilyl chloride.

It is appreciated that step a) is preferably carried out under an inertgas atmosphere. This is advantageous in order to drive out the onlyby-product of step a), i.e. ammonia, and thus increases the purity ofthe bis(silyl ether)phosphine obtained in step a). The inert gasatmosphere may be an argon, helium or nitrogen atmosphere.

It is one requirement of the present invention that the reaction betweenammonium hypophosphite and the silylating agent is carried out underheating for accelerating the reaction.

Preferably, step a) is thus carried out at a temperature in the rangefrom 100 to 130° C. For example, step a) is carried out at a temperaturein the range from 105 to 125° C. and most preferably in the range from110 to 120° C.

It is preferred that the equivalent weight ratio of silylating agent toammonium hypophosphite [silylating agent:ammonium hypophosphite] is from10:1 to 1:1, more preferably from 8:1 to 1:1, even more preferably from6:1 to 1:1 and most preferably from 5:1 to 1.5:1.

Step a) can be carried out with or without the addition of a solvent. Ifstep a) is carried out in a solvent, the solvent is preferably anorganic solvent, more preferably an aprotic organic solvent. Forexample, the organic solvent, more preferably the aprotic organicsolvent, is selected from the group comprising dichloromethane,tetrachloroethylene, tetrahydrofuran, 1,4-dioxane, toluene, benzene,xylene, and mixtures thereof. Most preferably, the organic solvent, morepreferably the aprotic organic solvent, is dichloromethane.

Preferably, step a) is carried out in the absence of an organic solvent.More preferably, step a) is carried out in the absence of a solvent.

Process step a) is preferably carried out under mixing the components,i.e. the silylating agent, ammonium hypophosphite and an optionalorganic solvent. The skilled man will adapt the mixing conditions (suchas the configuration of mixing tools and mixing speed) according to hisprocess equipment.

If step a) is carried out in the absence of a solvent, i.e. after thepreparation of the bis(silyl ether)phosphine, an organic solvent, morepreferably an aprotic organic solvent, is preferably added beforeprocess step b) is carried out. As outlined above, the organic solvent,more preferably the aprotic organic solvent, is selected from the groupcomprising dichloromethane, tetrachloroethylene, tetrahydrofuran,1,4-dioxane, toluene, benzene, xylene, and mixtures thereof. Mostpreferably, the organic solvent, more preferably the aprotic organicsolvent, is dichloromethane.

In one embodiment, the bis(silyl ether)phosphine obtained in step a) isthus dissolved in an organic solvent, more preferably an aprotic organicsolvent, before process step b) is carried out.

If the bis(silyl ether)phosphine obtained in step a) is mixed with anorganic solvent, more preferably an aprotic organic solvent, beforeprocess step b) is carried out, the bis(silyl ether)phosphine obtainedin step a) is preferably cooled down to a temperature in the range from−5 to 50° C., preferably in the range from 0 to 40° C., more preferablyin the range from 0 to 30° C., and most preferably in the range from 0to 25° C., e.g. from 0 to 10° C., before the organic solvent, morepreferably the aprotic organic solvent, is added.

The bis(silyl ether)phosphine obtained in step a) is subjected toprocess step b). Preferably, the bis(silyl ether)phosphine obtained instep a) is subjected to process step b) without purification andisolation of the silylated product obtained in step a).

In one embodiment, process step a) is repeated one or more times. Forexample, process step a) is repeated one or two times, e.g. one time.

Preferably, process step a) is carried out in one step and thus is notrepeated.

It is appreciated that process steps a) and b) can be performed in aone-pot-reaction. That is to say, the bis(silyl ether)phosphine isprepared in situ, without isolation or purification, and the compound ofthe general formula IIa and/or IIb is added to the bis(silylester)phosphine in the same reactor.

The following process step b) is carried out in that the bis(silylether)phosphine obtained in step a) is reacted with a compound of thegeneral formula IIa and/or IIb,

wherein R₁, R₂, R₃, R₄ and R₅ and/or R₇, R₈, R₉, R₁₀ and R₁₁ are asdefined above; Z is halogen.

With regard to the definition of the R₁, R₂, R₃, R₄, R₅, R₇, R₈, R₉, R₁₀and R₁₁ in general formula IIa and/or IIb and preferred embodimentsthereof, reference is made to the statements provided above whendiscussing the technical details of the bis(acyl)phosphinic acid silylester of the general formula I obtained by the process of the presentinvention.

As regards Z in in general formula IIa and/or IIb, it is appreciatedthat Z is a halogen. Preferably, Z is selected from chloro, bromo andiodo, more preferably chloro and bromo. Most preferably, Z is chloro.

Thus, in one embodiment the compound of the general formula IIa is acompound wherein R₁, R₂, R₃, R₄ and R₅ are the same or different and areindependently selected from H, halogen, linear or branched C₁-C₂₀-alkyl,linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy, C₂-C₈-alkenyloxy,C₃-C₈-cycloalkyl and C₆-C₁₂-aryl and Z is chloro. Preferably, R₁, R₂,R₃, R₄ and R₅ are the same or different and are independently selectedfrom H, halogen and, linear or branched C₁-C₂₀-alkyl and Z is chloro.Most preferably, R₁, R₂, R₃, R₄ and R₅ are the same or different and areindependently selected from H and linear or branched C₁-C₂₀-alkyl and Zis chloro.

Thus, it is preferred that one or more of R₁, R₂, R₃, R₄ and R₅ is/are Hand Z is chloro.

Additionally or alternatively, it is preferred that one or more of R₁,R₂, R₃, R₄ and R₅ is/are linear or branched C₁-C₂₀-alkyl, preferablylinear or branched C₁-C₁₈-alkyl, more preferably linear or branchedC₁-C₁₂-alkyl and most preferably linear C₁-C₈-alkyl, e.g. linearC₁-C₈-alkyl and Z is chloro. For example, one or more of R₁, R₂, R₃, R₄and R₅ is/are linear or branched C₁-C₆-alkyl, e.g. linear C₁-C₆-alkyl,preferably linear or branched C₁-C₄-alkyl, e.g. linear C₁-C₄-alkyl, andmost preferably linear or branched C₁-C₃-alkyl, e.g. linear C₁-C₃-alkyl,and Z is chloro. It is especially preferred that one or more of R₁, R₂,R₃, R₄ and R₅ is/are C₁- or C₂-alkyl, e.g. C₁-alkyl, and Z is chloro.

Preferably, R₁, R₃ and R₅ are the same and Z is chloro. In thisembodiment, R₁, R₃ and R₅ are preferably selected from H, halogen,linear or branched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl,C₁-C₈-alkoxy, C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl, C₆-C₁₂-aryl,C₃-C₈-cycloalkoxy, C₇-C₁₂-arylalkoxy, C₉-C₁₅-alkenylarylalkoxy, nitro-,C₆-C₁₂-arylsulfonyl, 4-alkylarylsulfonyl, C₁-C₂₀-alkylcarboxy,C₁-C₈-alkoxycarbonyl, SR₁₂, NHR₁₂ or NR₁₂R₁₃ with R₁₂ and R₁₃ beingindependently selected from H, linear or branched C₁-C₂₀-alkyl, linearor branched C₂-C₈-alkenyl and C₃-C₈-cycloalkyl, and an O-, S- orN-containing 5- or 6-membered heterocyclic ring, and Z is chloro. Forexample, R₁, R₃ and R₅ are the same and are selected from linear orbranched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy,C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl and an O-, S- or N-containing 5- or6-membered heterocyclic ring, and Z is chloro.

In one embodiment, R₁, R₃ and R₅ are the same and are linear or branchedC₁-C₂₀-alkyl, preferably linear or branched C₁-C₁₈-alkyl, morepreferably linear or branched C₁-C₁₂-alkyl and most preferably linearC₁-C₈-alkyl, e.g. linear C₁-C₈-alkyl, and Z is chloro. For example, R₁,R₃ and R₅ are the same and are linear or branched C₁-C₆-alkyl, e.g.linear C₁-C₆-alkyl, preferably linear or branched C₁-C₄-alkyl, e.g.linear C₁-C₄-alkyl, and most preferably linear or branched C₁-C₃-alkyl,e.g. linear C₁-C₃-alkyl, and Z is chloro. It is especially preferredthat R₁, R₃ and R₅ are the same and are C₁- or C₂-alkyl, e.g. C₁-alkyl,and Z is chloro.

In one embodiment, R₂ and R₄ are the same and Z is chloro. In thisembodiment, R₂ and R₄ are preferably selected from H, halogen, linear orbranched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy,C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl, C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy,C₇-C₁₂-arylalkoxy, C₉-C₁₅-alkenylarylalkoxy, nitro-,C₆-C₁₂-arylsulfonyl, 4-alkylarylsulfonyl, C₁-C₂₀-alkylcarboxy,C₁-C₈-alkoxycarbonyl, SR₁₂, NHR₁₂ or NR₁₂R₁₃ with R₁₂ and R₁₃ beingindependently selected from H, linear or branched C₁-C₂₀-alkyl, linearor branched C₂-C₈-alkenyl and C₃-C₈-cycloalkyl, and an O-, S- orN-containing 5- or 6-membered heterocyclic ring, and Z is chloro. Forexample, R₂ and R₄ are the same and are selected from H, linear orbranched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy,C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl and an O-, S- or N-containing 5- or6-membered heterocyclic ring, and Z is chloro.

In one embodiment, R₂ and R₄ are the same and are H, and Z is chloro.

It is appreciated that R₂ and R₄ are preferably different from R₁, R₃and R₅. Thus, if R₂ and R₄ are different from R₁, R₃, and R₅, R₂ and R₄are preferably the same and are H and R₁, R₃ and R₅ are the same and arelinear or branched C₁-C₂₀-alkyl, preferably linear or branchedC₁-C₁₈-alkyl, more preferably linear or branched C₁-C₁₂-alkyl and mostpreferably linear C₁-C₈-alkyl, e.g. linear C₁-C₈-alkyl, and Z is chloro.For example, R₂ and R₄ are the same and are H and R₁, R₃ and R₅ are thesame and are linear or branched C₁-C₆-alkyl, e.g. linear C₁-C₆-alkyl,preferably linear or branched C₁-C₄-alkyl, e.g. linear C₁-C₄-alkyl, andmost preferably linear or branched C₁-C₃-alkyl, e.g. linear C₁-C₃-alkyl,and Z is chloro. It is especially preferred that R₂ and R₄ are the sameand are H and R₁, R₃ and R₅ are the same and are C₁- or C₂-alkyl, e.g.C₁-alkyl, and Z is chloro.

Alternatively, if R₂ and R₄ are different from R₁, R₃, and R₅, R₂ and R₄are preferably the same and are C₁-C₈-alkoxy, preferably C₁-C₄-alkoxy,more preferably C₁-C₂-alkoxy, e.g. C₁-alkoxy, or halogen, preferably,chloro, bromo or iodo, more preferably chloro or bromo, e.g. chloro, andR₁, R₃ and R₅ are the same and are H, and Z is chloro. It is especiallypreferred that R₂ and R₄ are the same and are C₁-alkoxy and R₁, R₃ andR₅ are the same and are H, and Z is chloro. Alternatively, R₂ and R₄ arethe same and are chloro and R₁, R₃ and R₅ are the same and are H, and Zis chloro.

As regards R₇, R₈, R₉, R₁₀ and R₁₁ in the general formula IIb, it is tobe noted that they can be the same or different. Preferably, R₇, R₈, R₉,R₁₀ and R₁₁ are the same or different and are independently selectedfrom H, halogen, linear or branched C₁-C₂₀-alkyl, linear or branchedC₂-C₈-alkenyl, C₁-C₈-alkoxy, C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl,C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy, C₇-C₁₂-arylalkoxy,C₉-C₁₅-alkenylarylalkoxy, nitro-, C₆-C₁₂-arylsulfonyl,4-alkylarylsulfonyl, C₁-C₂₀-alkylcarboxy, C₁-C₈-alkoxycarbonyl, SR₁₂,NHR₁₂ or NR₁₂R₁₃ with R₁₂ and R₁₃ being independently selected from H,linear or branched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl andC₃-C₈-cycloalkyl, and an O-, S- or N-containing 5- or 6-memberedheterocyclic ring, and Z is chloro.

In one embodiment, R₇, R₈, R₉, R₁₀ and R₁₁ in the general formula IIbare the same or different and are independently selected from H,halogen, linear or branched C₁-C₂₀-alkyl, linear or branchedC₂-C₈-alkenyl, C₁-C₈-alkoxy, C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl andC₆-C₁₂-aryl, and Z is chloro. Preferably, R₇, R₈, R₉, R₁₀ and R₁₁ arethe same or different and are independently selected from H, halogenand, linear or branched C₁-C₂₀-alkyl, and Z is chloro. Most preferably,R₇, R₈, R₉, R₁₀ and R₁₁ are the same or different and are independentlyselected from H and, linear or branched C₁-C₂₀-alkyl, and Z is chloro.

Thus, it is preferred that one or more of R₇, R₈, R₉, R₁₀ and R₁₁ is/areH and Z is chloro.

Additionally or alternatively, it is preferred that one or more of R₇,R₈, R₉, R₁₀ and R₁₁ is/are linear or branched C₁-C₂₀-alkyl, preferablylinear or branched C₁-C₁₈-alkyl, more preferably linear or branchedC₁-C₁₂-alkyl and most preferably linear C₁-C₈-alkyl, e.g. linearC₁-C₈-alkyl, and Z is chloro. For example, one or more of R₇, R₈, R₉,R₁₀ and R₁₁ is/are linear or branched C₁-C₆-alkyl, e.g. linearC₁-C₆-alkyl, preferably linear or branched C₁-C₄-alkyl, e.g. linearC₁-C₄-alkyl, and most preferably linear or branched C₁-C₃-alkyl, e.g.linear C₁-C₃-alkyl, and Z is chloro. It is especially preferred that oneor more of R₇, R₈, R₉, R₁₀ and R₁₁ is/are C₁- or C₂-alkyl, e.g.C₁-alkyl, and Z is chloro.

Preferably, R₇, R₉ and R₁₁ are the same and Z is chloro. In thisembodiment, R₇, R₉ and R₁₁ are preferably selected from H, halogen,linear or branched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl,C₁-C₈-alkoxy, C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl, C₆-C₁₂-aryl,C₃-C₈-cycloalkoxy, C₇-C₁₂-arylalkoxy, C₉-C₁₅-alkenylarylalkoxy, nitro-,C₆-C₁₂-arylsulfonyl, 4-alkylarylsulfonyl, C₁-C₂₀-alkylcarboxy,C₁-C₈-alkoxycarbonyl, SR₁₂, NHR₁₂ or NR₁₂R₁₃ with R₁₂ and R₁₃ beingindependently selected from H, linear or branched C₁-C₂₀-alkyl, linearor branched C₂-C₈-alkenyl and C₃-C₈-cycloalkyl, and an O-, S- orN-containing 5- or 6-membered heterocyclic ring, and Z is chloro. Forexample, R₇, R₉ and R₁₁ are the same and are selected from linear orbranched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy,C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl and an O-, S- or N-containing 5- or6-membered heterocyclic ring, and Z is chloro.

In one embodiment, R₇, R₉ and R₁₁ are the same and are linear orbranched C₁-C₂₀-alkyl, preferably linear or branched C₁-C₁₈-alkyl, morepreferably linear or branched C₁-C₁₂-alkyl and most preferably linearC₁-C₈-alkyl, e.g. linear C₁-C₈-alkyl, and Z is chloro. For example, R₇,R₉ and R₁₁ are the same and are linear or branched C₁-C₆-alkyl, e.g.linear C₁-C₆-alkyl, preferably linear or branched C₁-C₄-alkyl, e.g.linear C₁-C₄-alkyl, and most preferably linear or branched C₁-C₃-alkyl,e.g. linear C₁-C₃-alkyl, and Z is chloro. It is especially preferredthat R₇, R₉ and R₁₁ are the same and are C₁- or C₂-alkyl, e.g. C₁-alkyl,and Z is chloro.

In one embodiment, R₈ and R₁₀ are the same and Z is chloro. In thisembodiment, R₈ and R₁₀ are preferably selected from H, halogen, linearor branched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl,C₁-C₈-alkoxy, C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl, C₆-C₁₂-aryl,C₃-C₈-cycloalkoxy, C₇-C₁₂-arylalkoxy, C₉-C₁₅-alkenylarylalkoxy, nitro-,C₆-C₁₂-arylsulfonyl, 4-alkylarylsulfonyl, C₁-C₂₀-alkylcarboxy,C₁-C₈-alkoxycarbonyl, SR₁₂, NHR₁₂ or NR₁₂R₁₃ with R₁₂ and R₁₃ beingindependently selected from H, linear or branched C₁-C₂₀-alkyl, linearor branched C₂-C₈-alkenyl and C₃-C₈-cycloalkyl, and an O-, S- orN-containing 5- or 6-membered heterocyclic ring, and Z is chloro. Forexample, R₈ and R₁₀ are the same and are selected from H, linear orbranched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy,C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl and an O-, S- or N-containing 5- or6-membered heterocyclic ring, and Z is chloro.

In one embodiment, R₈ and R₁₀ are the same and are H and Z is chloro.

It is appreciated that R₈ and R₁₀ are preferably different from R₇, R₉and R₁₁. Thus, if R₈ and R₁₀ are different from R₇, R₉ and R₁₁, R₈ andR₁₀ are preferably the same and are H and R₇, R₉ and R₁₁ are the sameand are linear or branched C₁-C₂₀-alkyl, preferably linear or branchedC₁-C₁₈-alkyl, more preferably linear or branched C₁-C₁₂-alkyl and mostpreferably linear C₁-C₈-alkyl, e.g. linear C₁-C₈-alkyl, and Z is chloro.For example, R₈ and R₁₀ are the same and are H and R₇, R₉ and R₁₁ arethe same and are linear or branched C₁-C₆-alkyl, e.g. linearC₁-C₆-alkyl, preferably linear or branched C₁-C₄-alkyl, e.g. linearC₁-C₄-alkyl, and most preferably linear or branched C₁-C₃-alkyl, e.g.linear C₁-C₃-alkyl, and Z is chloro. It is especially preferred that R₈and R₁₀ are the same and are H and R₇, R₉ and R₁₁ are the same and areC₁- or C₂-alkyl, e.g. C₁-alkyl, and Z is chloro.

Alternatively, if R₈ and R₁₀ are different from R₇, R₉ and R₁₁, R₈ andR₁₀ are preferably the same and are C₁-C₈-alkoxy, preferablyC₁-C₄-alkoxy, more preferably C₁-C₂-alkoxy, e.g. C₁-alkoxy, or halogen,preferably, chloro, bromo or iodo, more preferably chloro or bromo, e.g.chloro, and R₇, R₉ and R₁₁ are the same and are H, and Z is chloro. Itis especially preferred that R₈ and R₁₀ are the same and are C₁-alkoxyand R₇, R₉ and R₁₁ are the same and are H, and Z is chloro.Alternatively, R₈ and R₁₀ are the same and are chloro and R₇, R₉ and R₁₁are the same and are H, and Z is chloro.

In one embodiment, the bis(silyl ether)phosphine obtained in step a) isreacted with a compound of the general formula IIa (or IIb), wherein R₁,R₃ and R₅ (or R₇, R₉ and R₁₁) are the same and R₂ and R₄ (or R₈ and R₁₀)are the same and Z is chloro. Preferably, R₁, R₃ and R₅ in generalformula IIa (or R₇, R₉ and R₁₁ in general formula IIb) are the same andare C₁-alkyl and R₂ and R₄ (or R₈ and R₁₀) are the same and are H and Zis chloro. Alternatively, R₁, R₃ and R₅ in general formula IIa (or R₇,R₉ and R₁₁ in general formula IIb) are the same and are H and R₂ and R₄(or R₈ and R₁₀) are the same and are C₁-alkoxy, and Z is chloro.Alternatively, R₁, R₃ and R₅ in general formula IIa (or R₇, R₉ and R₁₁in general formula IIb) are the same and are H and R₂ and R₄ (or R₈ andR₁₀) are the same and are chloro, and Z is chloro. It is appreciatedthat this embodiment specifically results in the corresponding symmetricbis(acyl)phosphinic acid silyl ester of the general formula I, i.e. R₁,R₃, R₅, R₇, R₉ and R₁₁ are the same and R₂, R₄, R₈ and R₁₀ are the same.

Alternatively, the bis(acyl)phosphinic acid silyl ester obtained in stepa) is mixed with a compound of the general formula IIa and IIB, in whichR₁, R₃ and R₅ in general formula IIa are the same, R₇, R₉ and R₁₁ ingeneral formula IIb are the same, R₂ and R₄ in general formula IIa arethe same and R₈ and R₁₀ in general formula IIb are the same and Z ischloro. In this embodiment, R₁, R₃ and R₅ in general formula IIa aredifferent from R₇, R₉ and R₁₁ in general formula IIb and R₂ and R₄ ingeneral formula IIa are different from R₈ and R₁₀ in general formula IIband Z is chloro. It is thus appreciated that a mixed bis(acyl)phosphinicacid silyl ester of the general formula I is obtained if compounds ofthe general formula IIa and IIB are added in step b) of the presentprocess.

Step b) of the process of the present invention can be carried out overa wide temperature range. Thus, process step b) is preferably carriedout at a temperature in the range from −5 to 50° C., preferably in therange from 0 to 40° C., more preferably in the range from 0 to 30° C.,and most preferably in the range from 0 to 25° C.

The compound of the general formula IIa and/or IIb is preferably addeddropwise to the bis(silyl ether)phosphine obtained in step a). Thedropwise addition of the compound of the general formula IIa and/or IIbis preferably carried out at a temperature in the range from 0 to 25°C., e.g. from 0 to 10° C.

It is preferred that the reaction of the compound of the general formulaIIa and/or IIb with the bis(silyl ether)phosphine obtained in step a),i.e. after the addition of the compound of the general formula IIaand/or IIb, can be carried out at a temperature above the temperatureused for adding the compound of the general formula IIa and/or IIb.Thus, the reaction of the compound of the general formula IIa and/or IIbwith the bis(silyl ether)phosphine obtained in step a), i.e. after theaddition of the compound of the general formula IIa and/or IIb, ispreferably carried out at a temperature in the range from 0 to 25° C.,e.g. from 10 to 25° C. In one embodiment, the reaction of the compoundof the general formula IIa and/or IIb with the bis(silyl ether)phosphineobtained in step a), i.e. after the addition of the compound of thegeneral formula IIa and/or IIb, is carried out at about roomtemperature, i.e. 21° C.±2° C.

In view of the statements provided above with regard to process step a),it is appreciated that step b) is preferably carried out in the presenceof an organic solvent, preferably an aprotic organic solvent, e.g.dichloromethane.

It is appreciated that the compound of the general formula IIa and/orIIb is preferably added in step b) in an excess to the ammoniumhypophosphite of step a), based on the equivalent weight ratio.

It is preferred that the equivalent weight ratio of the compound of thegeneral formula IIa and/or IIb to the ammonium hypophosphite of step a)[IIa and/or IIb:P-compound] is in the range from 3.5:1 to 1.5:1 andpreferably in the range from 2.5:1 to 1.8:1.

Process step b) is preferably carried out under mixing the components,i.e. the silylating agent, the of the general formula IIa and/or IIb andthe optional organic solvent. The skilled man will adapt the mixingconditions (such as the configuration of mixing tools and mixing speed)according to his process equipment.

In one embodiment, process step b) is carried out without the additionof further additives.

Alternatively, process step b) is carried out in the presence of furtheradditives. For example, trimethylamine can be added in order to increasethe reactivity of the silylating agent.

It is appreciated that process step b) can be repeated one or moretimes. Preferably, process step b) is repeated one or two times, e.g.one time.

Accordingly, process step b) can be carried out in a one step procedure,i.e. without repeating the addition of the compound of the generalformula IIa and/or IIb, or in a stepwise procedure, repeating theaddition of the silylating agent followed by the compound of the generalformula IIa and/or IIb. If process step b) is carried out in a stepwiseprocedure, process step b) is thus repeated, preferably two times.

It is appreciated that the stepwise procedure is especially advantageousfor a controlled preparation of a bis(acyl)phosphinic acid silyl esterof the general formula I in high yield as the total stoichiometricallyrequired amount of the silylating agent is not added at once.Furthermore, the stepwise procedure allows the preparation of a definedmixed bis(acyl)phosphinic acid silyl ester of the general formula I.That is to say, the stepwise procedure is preferred if abis(acyl)phosphinic acid silyl ester of the general formula I isprepared, in which R₁, R₃ and R₅ are the same, R₇, R₉ and R₁₁ are thesame, R₂ and R₄ are the same and R₈ and R₁₀ are the same. Furthermore,R₁, R₃ and R₅ in general formula I are different from R₇, R₉ and R₁₁ andR₂ and R₄ are different from R₈ and R₁₀.

In one embodiment, the stepwise procedure allows the preparation of abis(acyl)phosphinic acid silyl ester of the general formula I, in whichR₁, R₂, R₃, R₄, R₅, R₆, R₇, R₈, R₉, R₁₀ and R₁₁ are the same ordifferent.

Preferably, process step b) is carried out in an one step procedure,i.e. without repeating the addition of the compound of the generalformula IIa and/or IIb.

It is appreciated that the bis(acyl)phosphinic acid silyl ester obtainedin step b) may be further treated by

-   -   i) separating the obtained bis(acyl)phosphinic acid silyl ester        of the general formula I from by-products and/or educts and/or        solvent, and/or    -   ii) washing the obtained bis(acyl)phosphinic acid silyl ester of        the general formula I.

Additionally, the bis(acyl)phosphinic acid silyl ester of the generalformula I obtained in step b) may be subjected to a drying step.

Thus, the process of the present invention may comprise further stepsfor isolating and/or purifying the obtained bis(acyl)phosphinic acidsilyl ester of the general formula I

Such steps are well known in the art and will be adapted by the skilledperson according to the process conditions and equipment used forcarrying out the process of the present invention.

In one embodiment, the process comprises a further step c) of mixing thebis(acyl)phosphinic acid silyl ester obtained in step b) with ethanolsuch as to obtain a bis(acyl)phosphinic acid of the general formula III

wherein R₁, R₂, R₃, R₄, R₅, R₇, R₈, R₉, R₁₀ and R₁₁ are the same ordifferent and are independently selected from H, halogen, linear orbranched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy,C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl, C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy,C₇-C₁₂-arylalkoxy, C₉-C₁₅-alkenylarylalkoxy, nitro-,C₆-C₁₂-arylsulfonyl, 4-alkylarylsulfonyl, C₁-C₂₀-alkylcarboxy,C₁-C₈-alkoxycarbonyl, SR₁₂, NHR₁₂ or NR₁₂R₁₃ with R₁₂ and R₁₃ beingindependently selected from H, linear or branched C₁-C₂₀-alkyl, linearor branched C₂-C₈-alkenyl and C₃-C₈-cycloalkyl, and an O-, S- orN-containing 5- or 6-membered heterocyclic ring; R₆ is OH

With regard to the definition of the R₁, R₂, R₃, R₄, R₅, R₇, R₈, R₉, R₁₀and R₁₁ in general formula III and preferred embodiments thereof,reference is made to the statements provided above when discussing thetechnical details of the bis(acyl)phosphinic acid silyl ester of thegeneral formula I obtained by the process of the present invention.

It is appreciated that the bis(acyl)phosphinic acid of the generalformula III is prepared by a specific process, namely a process avoidingthe use of metallic sodium or lithium in combination with undesirablephosphorus compounds such as white phosphorus, red phosphorus,phosphorus trichloride, alkyl or aryl phosphine, or dialkyl or diarylphosphine. Furthermore, the bis(acyl)phosphinic acid of the generalformula III can be easily prepared from the bis(acyl)phosphinic acidsilyl ester of the general formula I.

For obtaining the bis(acyl)phosphinic acid of the general formula III,subsequently to step b), the bis(acyl)phosphinic acid silyl esterobtained in step b) is hydrolysed.

It is appreciated that hydrolyzing of the bis(acyl)phosphinic acid silylester obtained in step b) can be achieved by using water and/or analcohol, such as methanol, ethanol, propanol. Preferably, step c) iscarried out by adding ethanol.

If the process of the present invention comprises step c), it isappreciated that process steps a), b) and c) can be performed in aone-pot-reaction. That is to say, the bis(silyl ether)phosphine isprepared in situ, without isolation or purification, the compound of thegeneral formula IIa and/or IIb is added to the bis(silyl ester)phosphinein the same reactor, without isolation or purification, and the obtainedbis(acyl)phosphinic acid silyl ester is hydrolysed in the same reactor.

Step c) of the process of the present invention can be carried out overa wide temperature range. However, for avoiding the formation ofunwanted by-products, step c) is preferably carried out at a temperaturein the range from −5 to 50° C., preferably in the range from 0 to 40°C., more preferably in the range from 0 to 30° C., and most preferablyin the range from 2 to 28° C. For example, process step c) is carriedout at a temperature in the range from 5 to 25° C.

Subsequent to process step c) of mixing the bis(acyl)phosphinic acidsilyl ester obtained in step b) with ethanol, the process may comprisefurther steps for isolating and/or purifying the obtainedbis(acyl)phosphinic acid of the general formula III.

For example, the process may further comprise a step of

-   -   i) separating the obtained bis(acyl)phosphinic acid of the        general formula III from the solvent, and/or    -   ii) washing the obtained bis(acyl)phosphinic acid of the general        formula III.

In one embodiment, the process further comprises the steps of

-   -   i) separating the obtained bis(acyl)phosphinic acid of the        general formula III from the solvent, and    -   ii) washing the obtained bis(acyl)phosphinic acid of the general        formula III.

Additionally, the process may further comprise a step of drying theobtained bis(acyl)phosphinic acid of the general formula III.

Such steps are well known in the art and will be adapted by the skilledperson according to the process conditions and equipment used forcarrying out the process of the present invention.

In one embodiment, the process comprises a further step d) ofhalogenating, preferably chlorinating, the bis(acyl)phosphinic acid ofthe general formula III obtained in step c) for obtaining a compound ofthe general formula IV

wherein R₁, R₂, R₃, R₄, R₅, R₇, R₈, R₉, R₁₀ and R₁₁ are the same ordifferent and are independently selected from H, halogen, linear orbranched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy,C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl, C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy,C₇-C₁₂-arylalkoxy, C₉-C₁₅-alkenylarylalkoxy, nitro-,C₆-C₁₂-arylsulfonyl, 4-alkylarylsulfonyl, C₁-C₂₀-alkylcarboxy,C₁-C₈-alkoxycarbonyl, SR₁₂, NHR₁₂ or NR₁₂R₁₃ with R₁₂ and R₁₃ beingindependently selected from H, linear or branched C₁-C₂₀-alkyl, linearor branched C₂-C₈-alkenyl and C₃-C₈-cycloalkyl, and an O-, S- orN-containing 5- or 6-membered heterocyclic ring; R₆ is halogen,preferably selected from chloro, bromo and iodo, more preferably chloro.

With regard to the definition of the R₁, R₂, R₃, R₄, R₅, R₇, R₈, R₉, R₁₀and R₁₁ in general formula IV and preferred embodiments thereof,reference is made to the statements provided above when discussing thetechnical details of the bis(acyl)phosphinic acid silyl ester of thegeneral formula I obtained by the process of the present invention.

Such halogenation reactions resulting in the halogenation of thebis(acyl)phosphinic acid of the general formula III are well known inthe art and can be adapted by the skilled person according to thespecific reaction and equipment used for carrying out the process of thepresent invention.

In another aspect, the present invention refers to a bis(acyl)phosphinicacid silyl ester of the general formula I,

wherein R₁, R₂, R₃, R₄, R₅, R₇, R₈, R₉, R₁₀ and R₁₁ are the same ordifferent and are independently selected from H, halogen, linear orbranched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy,C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl, C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy,C₇-C₁₂-arylalkoxy, C₉-C₁₅-alkenylarylalkoxy, nitro-,C₆-C₁₂-arylsulfonyl, 4-alkylarylsulfonyl, C₁-C₂₀-alkylcarboxy,C₁-C₈-alkoxycarbonyl, SR₁₂, NHR₁₂ or NR₁₂R₁₃ with R₁₂ and R₁₃ beingindependently selected from H, linear or branched C₁-C₂₀-alkyl, linearor branched C₂-C₈-alkenyl and C₃-C₈-cycloalkyl, and an O-, S- orN-containing 5- or 6-membered heterocyclic ring; R₆ is OSiR₁₄R₁₅R₁₆ withR₁₄, R₁₅ and R₁₆ being independently selected from linear or branchedC₁-C₂₀-alkyl or C₆-C₁₂-aryl. The bis(acyl)phosphinic acid silyl ester ofthe general formula I is preferably obtained by the process of thepresent invention.

With regard to the definition of the process, R₁, R₂, R₃, R₄, R₅, R₆,R₇, R₈, R₉, R₁₀ and R₁₁ in general formula I and preferred embodimentsthereof, reference is made to the statements provided above whendiscussing the technical details of the process as well as thebis(acyl)phosphinic acid silyl ester of the general formula I obtainedby the process of the present invention.

It is appreciated that the bis(acyl)phosphinic acid silyl ester of thegeneral formula I obtained by the process of the present invention ispreferably used for the preparation of bis(acyl)phosphinic acids.

In a further aspect, the present invention refers to abis(acyl)phosphinic acid of the general formula III,

wherein R₁, R₂, R₃, R₄, R₅, R₇, R₈, R₉, R₁₀ and R₁₁ are the same ordifferent and are independently selected from H, halogen, linear orbranched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy,C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl, C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy,C₇-C₁₂-arylalkoxy, C₉-C₁₅-alkenylarylalkoxy, nitro-,C₆-C₁₂-arylsulfonyl, 4-alkylarylsulfonyl, C₁-C₂₀-alkylcarboxy,C₁-C₈-alkoxycarbonyl, SR₁₂, NHR₁₂ or NR₁₂R₁₃ with R₁₂ and R₁₃ beingindependently selected from H, linear or branched C₁-C₂₀-alkyl, linearor branched C₂-C₈-alkenyl and C₃-C₈-cycloalkyl, and an O-, S- orN-containing 5- or 6-membered heterocyclic ring; R₆ is OH. Thebis(acyl)phosphinic acid of the general formula III is preferablyobtained by the process of the present invention.

With regard to the definition of the process, R₁, R₂, R₃, R₄, R₅, R₆,R₇, R₈, R₉, R₁₀ and R₁₁ in general formula III and preferred embodimentsthereof, reference is made to the statements provided above whendiscussing the technical details of the process as well as thebis(acyl)phosphinic acid silyl ester of the general formula I and thebis(acyl)phosphinic acid of the general formula III obtained by theprocess of the present invention.

It is appreciated that the bis(acyl)phosphinic acid of the generalformula III obtained by the process of the present invention ispreferably used in a photopolymerizable composition together with atleast one photopolymerizable unsaturated compound.

A further aspect of the present invention thus refers to aphotopolymerizable composition comprising the bis(acyl)phosphinic acidof the general formula III and at least one photopolymerizableunsaturated compound.

It is appreciated that any photopolymerizable unsaturated compound thatis typically used in the articles to be prepared and is well known canbe used as the at least one photopolymerizable unsaturated compound. Forexample, the at least one photopolymerizable unsaturated compound can bea compound as described in WO 2004/099262 A1 which is thus incorporatedherewith by reference.

The photopolymerizable composition may also contain optional additivesand/or optional further photoinitiators and/or coinitiator. The optionaladditives and/or photoinitiators and/or coinitiator are not limited anyinclude any additive and/or photoinitiators and/or coinitiator typicallyused in the articles to be prepared and are well known in the art. Forexample, the additives and/or photoinitiators and/or coinitiator can beone or more compounds described as additives (C) and/or photoinitiatorsand/or coinitiator (D) in WO 2004/099262 A1 which is thus incorporatedherewith by reference.

The scope and interest of the invention will be better understood basedon the following examples which are intended to illustrate certainembodiments of the invention and are non-limitative.

EXAMPLES Example 1: Synthesis of Bis(2,4,6-trimethylbenzoyl)phosphinicAcid, Stepwise Procedure

Ammonium hypophosphite (20.0 g, 0.241 mol, 1 eq) was suspended in 68.04g (0.422 mol, 1.75 eq) 1,1,1,3,3,3-hexamethyldisilazane and stirred at110-120° C. until ammonia evolution ceased and the ammoniumhypophosphite was completely dissolved. The reaction mixture was cooleddown to 5° C. in an ice bath and diluted with 200 mL of dichloromethane.44.44 g (0.243 mol, 1.01 eq) 2,4,6-trimethylbenzoyl chloride was addeddropwise and the reaction mixture stirred overnight at room temperature.The flask was again cooled down in an ice bath and another 68.04 g(0.422 mol, 1.75 eq) of 1,1,1,3,3,3-hexamethyldisilazane were quicklyadded. After three hours of stirring at 5° C., 44.44 g (0.243 mol, 1.01eq) 2,4,6-trimethylbenzoyl chloride was added dropwise and leftovernight with stirring at room temperature. The reaction mass was thencooled down to 0-5° C. and hydrolyzed by dropwise addition of 200 mLethanol, so that the temperature did not exceed 15° C. After filtration,the residue was thoroughly washed with ethanol and the filtrateevaporated to dryness. To the yellow viscous oil was added TBME:hexane1:1. After the product had crystallized, the slightly yellow solid wasfiltered, washed with cold hexane and dried.

Yield: 53.8 g of a pale yellow solid, 62% of theory

¹H-NMR (400.13 MHz; CDCl₃): δ (ppm)=2.13 (s, 12H), 2.26 (s, 6H), 6.77(s, 4H), 9.53 (bs, 1H)

³¹P-NMR (161.89 MHz; CDCl₃): δ (ppm)=−3.67

¹³C-NMR (100.62 MHz; CDCl₃): (ppm) δ=19.25, 21.15, 128.70, 135.15,136.23 (d, ³J_(PC) 45.5 Hz), 140.23, 216.80 (d, ¹J_(PC) 101.2 Hz)

The total formula was confirmed by elemental analysis. The elementalanalysis was carried out by a standard procedure.

Example 2: Synthesis of Bis(2,4,6-trimethylbenzoyl)phosphinic Acid,One-Step Procedure

Ammonium hypophosphite (20.0 g, 0.241 mol, 1 eq) were suspended in136.07 g (0.843 mol, 3.5 eq) 1,1,1,3,3,3-hexamethyldisilazane andstirred at 110-120° C. until ammonia evolution ceased and the ammoniumhypophosphite dissolved completely. The reaction mixture was cooled downto 5° C. in an ice bath and diluted with 200 mL of dichloromethane.90.19 g (0.494 mol, 2.05 eq) 2,4,6-trimethylbenzoyl chloride was addeddropwise and the reaction mixture was stirred overnight at roomtemperature until ³¹P-NMR showed complete conversion. Subsequently, thereaction mass was cooled to 0-5° C. and hydrolyzed by dropwise additionof 300 mL ethanol so that the temperature did not exceed 25° C. Afterfiltration, the residue was thoroughly washed withdichloromethane:ethanol 1:1 and the filtrate evaporated to dryness. Theresidue was dissolved in ethyl acetate and washed twice with dilutehydrochloric acid. The organic phase was dried and evaporated. The crudesolid product was recrystallized from a mixture of heptane:toluene 1:4filtered, washed with heptane and dried to givebis(2,4,6-trimethylbenzoyl)phosphinic acid as a pale yellow solid.

Yield: 62.1 g pale yellow solid, 72% of theory

¹H-NMR (400.13 MHz; CDCl₃): δ=2.13 (s, 12H), 2.32 (s, 6H), 6.97 (s, 4H),12.65 (bs, 1H)

³¹P-NMR (161.89 MHz; CDCl₃): δ=−2.97

¹³C-NMR (100.62 MHz; CDCl₃): δ=19.14, 21.27, 128.79, 135.26 (d, ²J_(PC)46.5 Hz), 135.46, 140.67, 213.72 (d, ¹J_(PC) 98.7 Hz)

Correct elemental analysis was obtained. The elemental analysis wascarried out by a standard procedure.

The invention claimed is:
 1. A process for the preparation of abis(acyl)phosphinic acid silyl ester of the general formula I:

wherein R₁, R₂, R₃, R₄, R₅, R₇, R₈, R₉, R₁₀ and R₁₁ are the same ordifferent and are independently selected from H, halogen, linear orbranched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy,C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl, C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy,C₇-C₁₂-arylalkoxy, C₉-C₁₅-alkenylarylalkoxy, nitro-,C₆-C₁₂-arylsulfonyl, 4-alkylarylsulfonyl, C₁-C₂₀-alkylcarboxy,C₁-C₈-alkoxycarbonyl, SR₁₂, NHR₁₂ or NR₁₂R₁₃ with R₁₂ and R₁₃ beingindependently selected from H, linear or branched C₁-C₂₀-alkyl, linearor branched C₂-C₈-alkenyl and C₃-C₈-cycloalkyl, and an O-, S- orN-containing 5- or 6-membered heterocyclic ring; R₆ is OSiR₁₄R₁₅R₁₆ withR₁₄, R₁₅ and R₁₆ being independently selected from linear or branchedC₁-C₂₀-alkyl or C₆-C₁₂-aryl, the process comprising the steps of a)heating ammonium hypophosphite with a silylating agent for obtaining abis(silyl ether)phosphine, and b) reacting the bis(silyl ether)phosphineobtained in step a) with a compound of the general formula IIa and/orIIb,

wherein R₁, R₂, R₃, R₄ and R₅ and/or R₇, R₈, R₉, R₁₀ and R₁₁ are asdefined above; Z is halogen.
 2. The process according to claim 1,wherein R₁, R₃ and R₅ and/or R₇, R₉ and R₁₁ are the same.
 3. The processaccording to claim 2, wherein R₁, R₃ and R₅ and/or R₇, R₉ and R₁₁ arethe same and are selected from linear or branched C₁-C₂₀-alkyl.
 4. Theprocess according to claim 1, wherein R₂ and R₄ and/or R₈ and R₁₀ arethe same.
 5. The process according to claim 1, wherein R₂ and R₄ and/orR₈ and R₁₀ are the same and are H.
 6. The process according to claim 1,wherein Z is selected from chloro, bromo and iodo.
 7. The processaccording to claim 1, wherein step a) is carried out under an inert gasatmosphere and/or without the addition of a solvent.
 8. The processaccording to claim 1, wherein the bis(silyl ether)phosphine obtained instep a) is mixed with an organic solvent before process step b) iscarried out.
 9. The process according to claim 1, wherein the bis(silylether)phosphine obtained in step a) is subjected to process step b)without purification and isolation of the silylated product obtained instep a).
 10. The process according to claim 1, wherein step a) iscarried out at a temperature in the range from 100 to 130° C. and/orstep b) is carried out at a temperature in the range from −5 to 50° C.11. The process according to claim 1, wherein step b) is carried out inthat the equivalent weight ratio of the compound of the general formulaIIa and/or IIb to the ammonium hypophosphite of step a) [IIa and/orIIb:P-compound] is in the range from 3.5:1 to 1.5:1.
 12. The processaccording to claim 1, wherein process step a) and/or step b) is repeatedone or more times.
 13. The process according to claim 1, wherein theprocess comprises a further step c) of hydrolyzing thebis(acyl)phosphinic acid silyl ester obtained in step b) such as toobtain a bis(acyl)phosphinic acid of the general formula III:

wherein R₁, R₂, R₃, R₄, R₅, R₇, R₈, R₉, R₁₀ and R₁₁ are the same ordifferent and are independently selected from H, halogen, linear orbranched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy,C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl, C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy,C₇-C₁₂-arylalkoxy, C₉-C₁₅-alkenylarylalkoxy, nitro-,C₆-C₁₂-arylsulfonyl, 4-alkylarylsulfonyl, C₁-C₂₀-alkylcarboxy,C₁-C₈-alkoxycarbonyl, SR₁₂, NHR₁₂ or NR₁₂R₁₃ with R₁₂ and R₁₃ beingindependently selected from H, linear or branched C₁-C₂₀-alkyl, linearor branched C₂-C₈-alkenyl and C₃-C₈-cycloalkyl, and an O-, S- orN-containing 5- or 6-membered heterocyclic ring; R₆ is OH.
 14. Theprocess according to claim 13, wherein step c) is carried out at atemperature in the range from −5 to 50° C.
 15. A bis(acyl)phosphinicacid silyl ester of the general formula I:

wherein R₁, R₂, R₃, R₄, R₅, R₇, R₈, R₉, R₁₀ and R₁₁ are the same ordifferent and are independently selected from H, halogen, linear orbranched C₁-C₂₀-alkyl, linear or branched C₂-C₈-alkenyl, C₁-C₈-alkoxy,C₂-C₈-alkenyloxy, C₃-C₈-cycloalkyl, C₆-C₁₂-aryl, C₃-C₈-cycloalkoxy,C₇-C₁₂-arylalkoxy, C₉-C₁₅-alkenylarylalkoxy, nitro-,C₆-C₁₂-arylsulfonyl, 4-alkylarylsulfonyl, C₁-C₂₀-alkylcarboxy,C₁-C₈-alkoxycarbonyl, SR₁₂, NHR₁₂ or NR₁₂R₁₃ with R₁₂ and R₁₃ beingindependently selected from H, linear or branched C₁-C₂₀-alkyl, linearor branched C₂-C₈-alkenyl and C₃-C₈-cycloalkyl, and an O-, S- orN-containing 5- or 6-membered heterocyclic ring; R₆ is OSiR₁₄R₁₅R₁₆ withR₁₄, R₁₅ and R₁₆ being independently selected from linear or branchedC₁-C₂₀-alkyl or C₆-C₁₂-aryl, obtained by a process according to claim 1.